The deployment of optoelectronic devices such as photovoltaic cells on a large scale requires the use of thin film technologies so as to save in terms of primary material as well as for increasing the flow of production.
Most of the optoelectronic devices use silicon semiconductor components. Indeed, Silicon is an abundant element that is well controlled technologically.
However, Silicon in its diamond-like crystal phase has a small absorption coefficient in particular in the visible spectrum. A consequence of such weak absorption properties of Silicon is to require the use of great thickness of material (about 200 μm) to make effective optoelectronic devices, such as photovoltaic cells.
This has recently (early XXIst century) caused an increase in the price of Silicon crystal following a significant increase of the demand of Silicon crystal.
Moreover, the use of great thicknesses of materials requires the use of highly pure and very well crystallized Silicon and enforces strong constraints on the processes, which are the principal obstacles to the reduction of the costs.
Other materials may be used to manufacture thin film optoelectronic devices, such as photovoltaic cells having an active layer of the order of a few micrometers.
For example, one may use a-Si:H material to replace crystalline silicon in the active layer. However, the optoelectronic devices obtained by replacing the crystalline silicon by a-Si:H are not as efficient as the one comprising an active layer made of crystalline silicon.
The use of CdTe, CIGS active layers presents the drawback of being less developed technologically and using scarce elements.